#include<stdio.h>
int main()
{
    float score;
    printf("please input grade: ");
    scanf("%f",&score);
    if(score<0||score>100)
    {
        printf("error\n");
    }
    else{
        if(score>=90){
            printf("A\n");
        }
        else
        if(score>=80){
            printf("B\n");
        }
        else{
            if(score>=70);
            printf("C\n");
        }
        else
        if(score>=60);
        printf("D\n");
    }
    else {printf("E\n");}
}